CVE-2021-29446Network attack vector

Plaintext recovery via CBC padding timing oracle

Published Apr 16, 2021 · Updated Aug 3, 2024

Padding-oracle exposure in Panva jose-node-cjs-runtime before 3.11.4 allows remote attackers to recover JWE plaintext through timing. The AES_CBC_HMAC_SHA2 decryption path performs CBC decryption even when HMAC authentication fails, so padding-error timing becomes an oracle. Exploitation requires repeated chosen-ciphertext requests to an application that exposes this library's JWE decryption path, averaging 128 queries per ciphertext-block byte.

CVSS severity5.9
Medium
EPSS probability1.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Padding-oracle exposure in Panva jose-node-cjs-runtime before 3.11.4 allows remote attackers to recover JWE plaintext through timing. The AES_CBC_HMAC_SHA2 decryption path performs CBC decryption even when HMAC authentication fails, so padding-error timing becomes an oracle. Exploitation requires repeated chosen-ciphertext requests to an application that exposes this library's JWE decryption path, averaging 128 queries per ciphertext-block byte.

The record

CVE
CVE-2021-29446
Published
Apr 16, 2021
Updated
Aug 3, 2024
Vendor
Panva
Product
jose-node-cjs-runtime
Classifications
CWE-696, CWE-208, CWE-203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.11.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Panva · jose-node-cjs-runtimeversion=< 3.11.4

Published CVSS scores

5.9NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
5.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:P/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-696Incorrect Behavior Order
CWE-208Observable Timing Discrepancy
CWE-203Observable Discrepancy

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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